1. Field of the Invention
This invention relates generally to the field of electronic component packaging, and more particularly to packaging for integrated circuits which can provide a low noise circuit environment.
2. Description of Prior Art
Packages for electronic circuit components provide the mechanical protection so that these components may be easily handled. Of necessity all packages must provide electrical leads or feed-throughs to connect the components within the package to the electronic system outside the package. These leads are usually arranged in several tightly spaced rows, and can typically be found either on two opposing sides of the package, on all four sides, or along the bottom of the package.
In previous packaging schemes, the dielectric which seals the leads of the package has had to serve a dual purpose. First, it must be workable during package construction such that it flows well around the leads and then cools with a hermetic seal without cracking. Secondly, the dielectric material should ideally produce a minimal amount of 'dielectric noise' which in some instances can degrade the performance of the electronic components inside the package. The effects of dielectric noise can be especially unwelcome for circuitry interacting with extremely small signal levels in a high impedance environment.
Unfortunately, the lowest noise dielectrics (e.g. diamond, sapphire, quartz, beryllium oxide, Corning 7070 glass) do not lend themselves to standard package construction techniques and therefore most packages compromise noise performance in order to form a more perfect seal.
As is well known in the art, a traditional hybrid integrated circuit (IC) package comprises a housing and a lid. The housing comprises a base and four sidewalls and is fabricated using plastic, ceramic, or metal, or a combination thereof. Electrical feed-throughs, or leads, pass through the base or sides of the housing in two or more tightly spaced rows. After the circuit components are attached inside the housing, either directly or first by being attached to a flat substrate material, the circuit components are connected together and to the electrical leads. Lastly, a flat lid is attached to the housing using one of several sealing methods, such as by soldering or by using an epoxy preform. All electrical connections are made through the housing using the feed-throughs which are isolated from the housing.